1. Field of the Invention
The present invention provides a method for treating plants by spraying plants with Pink Pigmented Facultative Methylotroph (PPFM) either alone or in combination with methanol during growth.
2. Discussion of the Background
Improvements in crop yields is a highly active area of research, and as a result, today's farms are much more productive than their counterparts from a century ago. However, as the world's population increases with a concomitant decrease in farming resources, more and more emphasis is being placed on enhancing crop yields. Farmers are presently seeking ways to expand their yields while limiting the use of dangerous fertilizers and pesticides. An avenue of research which has developed from the desire to avoid harmful chemical crop treatments is the treatment of seeds or the soil with non-toxic crop augmenter prior to sowing.
Schroth et al, U.S. Pat. No. 4,849,008, describes enhancing root crop yields by treating plant seeds with a specific growth promoting bacterial strain of the genus Pseudomonas. The bacterial strains may be applied with a liquid carrier or in a paste.
Williams, U.S. Pat. No. 5,106,648, refers to a method of preparing coated seeds by slurrying seeds with a microorganism, which has a beneficial effect on plants which grow from these seeds, a carrier medium and an adhesive polymer. This method is supposed to maintain microorganisms viable for extended periods of time.
Mann, U.S. Pat. No. 4,061,488, addresses treatment of plant seeds with spores from Bacillus uniflagellatus to enhance plant growth. It is suspected that root growth triggers the germination of these spores.
Polacco et al, U.S. Pat. No. 5,268,171, describe a method of altering the metabolism of a plant includes the steps of genetically altering at least one commensal bacterium of the plant to alter the level and nature of urease activity produced by the plant.
Holland et al, U.S. Pat. No. 5,512,069, which is incorporated herein in its entirety, describes methods for increasing the germination of seeds by coating or impregnating them with PPFMs. PPFMs were first described in connection with plants more than 20 years ago when it was demonstrated that cell cultures of the leafy liverwort Scapania are routinely associated with PPFMs (Basile et al, 1985, The Bryologist 88(2):77). Since then these bacteria have been shown to be universally associated with plants, but the exact nature of the relationships has remained obscure.
Nonomura and Benson, Proc. Nat'l. Acad. Sci. U.S.A., 89, 9794 (1992) teach that foliar sprays of aqueous (10-50%) methanol increased growth and yield of C3 crop plants in arid environments.
Nishio et al, in Proceedings of Twentieth Annual Meeting Plant Growth Regulator Society of America, Ferguson, ed., pp. 8-13, 1993, teach that a 30% increase in dry matter and accelerated rate of development of soybean plants can be achieved with a foliar-applied 15% methanol with fertilizer on a daily rotated basis.
Moore et al, U.S. Pat. No. 4,297,130 teach a method for the foliar feeding of leguminous plants with a nonburning nitrogenous plant food which is applied to the foliage of he plant at the R1-R4 flowering stage.
Joshi, U.S. Pat. No. 5,532,204, which is incorporated by reference herein in its entirety, teaches a method of fertilizing leguminous plants for increase yield using methanol and urea based nitrogen fertilizer.
Despite these teachings, the use of methanol has not become routine in commercial application. Two reasons for this may be that (1) the treatment is not universally effective under all cultural conditions or on all crops; and (2) the mechanism by which methanol works to affect yield has not been demonstrated convincingly.
Because methanol applications seemed to be most effective under high light conditions and in C3 plants, it was suggested that methanol works by inhibiting photorespiration (Nonomura et al, 1992, Proc. Natl. Acad. Sci. USA 89:9794-9798). This idea was supported by the observations that the treatment was enhanced by the addition of glycine to the spray mixture and that C4 plants (in which photorespiration is already low) did not respond. Fall and Benson (1996, Trends in Plant Sci. 1: 296-301) have elaborated on this explanation, suggesting possible alterations in metabolism that would result in a greater than normal return of photorespiratory carbon to the chloroplast. However, further studies have complicated the picture, and thus the mechanism by which methanol affects plant growth is not clear.
Moreover, despite the above knowledge, producers of crop plants report "hit or miss" success with the above methods. Accordingly, a method which provides reproducible increases in growth and yield is desirable.